Impact of the chaotic semiconductor laser output power on time-delay-signature of chaos and random bit generation

We experimentally analyze the effect of the optical power on the time delay signature identification and the random bit generation in chaotic semiconductor laser with optical feedback. Due to the inevitable noise during the photoelectric detection and analog-digital conversion, the varying of output optical power would change the signal to noise ratio, then impact time delay signature identification and the random bit generation. Our results show that, when the optical power is less than −14 dBm, with the decreasing of the optical power, the actual identified time delay signature degrades and the entropy of the chaotic signal increases. Moreover, the extracted random bit sequence with lower optical power is more easily pass through the randomness testing.